Martin Rees, The Astronomer Royal. Whatever part of the world we live in we're going to have to contend with the fact that the world is getting more crowded and that each individual is going to become more demanding of resources, energy and food. If we are to cope with this more crowded world we are going to have to deploy science and technology in a more optimum way, a way that requires international partnerships. Martin Rees presents the case that scientists have a special role to play in promoting this discussion amongst the general public and politicians so that important long term issues remain high on the agenda. Presented at the Learning Without Frontiers Conference, London, January 26th, 2012. http://www.learningwithoutfrontiers.com/